docs: def stop_NoteContainer(self, nc, channel=1):
          """Stop playing the notes in NoteContainer nc."""
          self.notify_listeners(self.MSG_PLAY_NC, {'notes': nc,
              'channel': channel})
          if nc is None:
              return True
          for note in nc:
              if not self.stop_Note(note, channel):
                  return False
          return True